Will you be preaching the traditional Christmas story from Luke? Or perhaps you will take a different perspective and focus on John's beautiful prologue, read in some traditions as a "second gospel." I first heard it read that way--at the end of a magnificent midnight service--my last year of seminary when I was lucky enough to serve on the altar at the Cathedral of St. John the Divine in New York City, and while I had never particularly associated that passage with Christmas, hearing it in that context changed the way I thought about it for ever.
Will you celebrate both Christmas Eve and Christmas Day? Will you have a pageant? Will you be up all night wrapping presents after the late service on Christmas Eve (my usual habit)? What are your plans for this most holy time?